Julie Townsend

Athlete: A cargo handling and manipulation robot for the moon

A robotic vehicle called ATHLETE—the All-Terrain Hex-Limbed, Extra-Terrestrial Explorer—is described, along with initial results of field tests of two prototype vehicles. This vehicle concept is capable of efficient rolling mobility on moderate terrain and walking mobility on extreme terrain. Each limb has a quick-disconnect tool adapter so that it can perform general-purpose handling, assembly, maintenance, and servicing tasks using any or all of the limbs.

ATHLETE mobility performance with active terrain compliance

The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) is a modular, heavy-lift vehicle being developed to support NASA operations on the lunar surface. This agile system consists of a symmetrical arrangement of six limbs, each with six articulated degrees of freedom and a powered wheel. The design enables transport of bulky payloads over a wide range of terrains and is envisioned as a tool to mobilize habitats, power generation equipment, and other supplies in for long-range lunar exploration and lunar outpost construction. The first-generation prototype transports payloads of up to 300 kg in terrestrial testing, with flight models projected to carry at least 15 metric tons in a lunar gravity environment. 1 2

The Lemur II-Class Robots for Inspection and Maintenance of Orbital Structures: A System Description

The assembly, inspection, and maintenance requirements of permanent installations in space demand robots that provide a high level of operational flexibility relative to mass and volume. Such demands point to robots that are dexterous, have significant processing and sensing capabilities, and can be easily reconfigured (both physically and algorithmically). Evolving from Lemur I, Lemur IIa is an extremely capable system that both explores mechanical design elements and provides an infrastructure for the development of algorithms (such as force control for mobility and manipulation and adaptive visual feedback). The physical layout of the system consists of six, 4-degree-of-freedom limbs arranged axisymmetrically about a hexagonal body platform. These limbs incorporate a “quick-connect” end-effector feature below the distal joint that allows the rapid change-out of any of its tools. The other major subsystem is a stereo camera set that travels along a ring track, allowing omnidirectional vision. The current Lemur IIa platform represents the jumping-off point toward more advanced robotic platforms that will support NASA’s Vision for Space Exploration, which calls for a sustained presence in space. This paper lays out the mechanical, electrical, and algorithmic elements of Lemur IIa and discusses the future directions of development in those areas.

Modular Additive Construction Using Native Materials

Using modular construction equipment and additive manufacturing (3D printing) techniques for binding, mission support structures could be prepared on remote planetary surfaces using native regolith. Material mass contributes significantly toward the cost of deep space missions, whether human or robotic, due to the resources needed to lift each kilogram of equipment out of Earth’s gravity well. Proposing the modular Freeform Additive Construction System (FACS) concept, using the reconfigurable All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) robotic mobility platform, a variety of walls, berms, vaults, domes, paving, and thick radiation shielding could be prepared in advance of crews and mission assets to help reduce the material needed to be brought from Earth. This paper discusses the current ATHLETE technology, and describes how flexible mission elements could be derived using a combination of three dimensional additive construction and in-situ manufacturing technologies using native regolith.

Vision-guided self-alignment and manipulation in a walking robot

One of the robots under development at the NASAs Jet Propulsion Laboratory (JPL) is the limbed excursion mechanical utility robot, or LEMUR. Several of the tasks slated for this robot require computer vision, as a system, to interface with the other systems in the robot, such as walking, body pose adjustment, and manipulation. This paper describes the vision algorithms used in several tasks, as well as the vision-guided manipulation algorithms developed to mitigate mismatches between the vision system and the limbs used for manipulation. Two system-level tasks are described, one involving a two meter walk culminating in a bolt-fastening task and one involving a vision-guided alignment ending with the robot mating with a docking station

Mars Exploration Rovers 2004-2013: Evolving Operational Tactics Driven by Aging Robotic Systems

Over the course of more than 10 years of continuous operations on the Martian surface, the operations team for the Mars Exploration Rovers has encountered and overcome many challenges. The twin rovers, Spirit and Opportunity, designed for a Martian surface mission of three months in duration, far outlived their life expectancy. Spirit explored for six years and Opportunity still operates and, in January 2014, celebrated the 10th anniversary of her landing. As with any machine that far outlives its design life, each rover has experienced a series of failures and degradations attributable to age, use, and environmental exposure. This paper reviews the failures and degradations experienced by the two rovers and the measures taken by the operations team to correct, mitigate, or surmount them to enable continued exploration and discovery.

Sliding GAIT Algorithm for the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE)

The design of a surface robotic system typically involves a trade between the traverse speed of a wheeled rover and the terrain-negotiating capabilities of a multi-legged walker. The ATHLETE mobility system, with both articulated limbs and wheels, is uniquely capable of both driving and walking and has the flexibility to employ additional hybrid mobility modes. This paper introduces the Sliding Gait, an intermediate mobility algorithm faster than walking with better terrain-handling capabilities than wheeled mobility.Copyright

Driving ATHLETE: Analysis of Operational Efficiency

The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) is a modular mobility and manipulation platform being developed to support NASA operations in a variety of missions, including exploration of planetary surfaces. The agile system consists of a symmetrical arrangement of six limbs, each with seven articulated degrees of freedom and a powered wheel. This design enables transport of bulky payloads over a wide range of terrain and is envisioned as a tool to mobilize habitats, power-generation equipment, and other supplies for long-range exploration and outpost construction. In 2010, ATHLETE traversed more than 80 km in field environments over eight weeks of testing, demonstrating that the concept is well suited to long-range travel. However, while ATHLETE is designed to travel at speeds of up to 5 kilometers per hour, the observed average traverse rate during field-testing rarely exceeded 1.5 kilometers per hour. This paper investigates sources of inefficiency in ATHLETE traverse operations and identifies targets for improvement of overall traverse rate.